PET-CT: Modality 0008,0060 for CT Image Storage

[Mathieu Malaterre]

Could someone please confirm what is the expected value for Modality 0008,0060 attribute in a PET-CT type acquisition ?

So far we found out that the following three devices:

GE MEDICAL SYSTEMS,Discovery IQ
GE MEDICAL SYSTEMS,Discovery MI
SIEMENS ,Biograph 40

are generating CT Image Storage (1.2.840.10008.5.1.4.1.1.2) instances with a Modality value set to "PT".

I agree that for legacy IODs (C.7.3.1 General Series Module) there is no restriction for Modality value, but since this would cause some hiccups for Legacy Converted Enhanced CT Image IOD I was wondering what people were doing ?

Are you updating the "PT" Modality value to the expected "CT" directly in the legacy instances, or do you change it on the fly when requested for new enhanced SOP classes ?

Thanks for comments,